Centrifugal pipe casting machine



Sept. 1, 1959 R. w. KURTZ CENTRIFUGAL PIPE CASTING MACHINE Filed July29, .1957

3 Sheets-Sheet -1 Sept. 1, 1959 R. w. KURTZ 2,901,793

CENTRIFUGAL PIPE CASTING MACHINE Filed July 29, 1957 5 Sheets-Sheet 2 /ZJ9 O l O 59 68 66 9a 9 I v I J7 Sept. 1, 1959 R. w. KURTZ CENTRIFUGALPIPE CASTING MACHINE Filed July 29, 1957 3 Sheets-Sheet 3 2,901,193 1C6Patented Sept. 1, 1959 CENTRIFUGAL PIPE CASTING MACHINE Ralph W. Kurtz,Coshocton, Ohio, assignor to James B. Clow & Sons, Inc., Coshocton,Ohio, a corporation of Delaware Application July 29, 1957, Serial No.674,748 7 Claims. (CI. 22-65) This invention relates to the casting oftubular products; particularly to the casting of iron pipes,centrifugally, in tubular steel molds.

These molds, for the most part, have a length several times as great astheir diameter. Their strength as beams is not so great but what theytend to warp slightly in service, unless constrained, and form portionsof the pipe eccentrically.

Molds for pipes having a nominal diameter less than about five inchescan be reinforced very well by a surrounding sleeve, such as thatdescribed in this applicants Patent No. 2,586,349. A better scheme formounting larger molds is revealed herein, a scheme that employsrelatively convenient and powerful equipment.

In lieu of a sleeve, rollers are used to both support and steady themold. Warpage of the mold is resisted by air cylinders, remotelycontrolled and applicable to whatever extent is needed. The rollers aremounted on axles which are supported in the machine housing without theaid of bolts. Grease is sealed in the rollers by long-wearing plasticrings. The mold is retained axially by a collar clamped thereto andlubricated automatically, by water.

In the accompanying drawings:

Figure 1 is a side elevational view, partly exploded, of a castingmachine that embodies a preferred form of this invention;

Figure 2 is a transverse sectional view taken along the line 2-2 ofFigure 1 (a similar view is had at two locations);

Figure 3 is a side sectional view of one of the rollers; and Figure 4 isa fragmentary sectional view of the rotor taken along the line 4-4 ofFigure 2.

Not shown, but well known in this art, is equipment used to pour moltenmetal into the mold; and, tackle employed to extract the cast product.Depicted is the centrifugating unit only, an apparatus constituted bythree principal sub-assemblies; a rotor equipped with sealing girts, alower box-half 50 supporting the rotor, and an upper box-half 90supporting a motor.

An annular chamber 11, defined. by the box-halves 50, 9t) and thebegirted rotor, is filled with hot water under pressure when castingpipes. All parts within the chamber are subjected to a washing andcorrosive action. Also, and since it is sometimes necessary or expedientto jar the cast product loose from the mold, the parts must beconstructed in a more rugged manner than would otherwise be necessary.

As best shownin'Figure 4, the rotor 10 comprises a tubular mold 12 andvarious appurtenances. A sealing collar 13 has packed engagement withthe axially inner side of a shoulder 14 projecting radially outwardlyfrom an enlarged, or bell, end of the mold. A series of screws 15 servesto clamp the shoulder 14 tightly between the collar 13 and a core frame16 mounted in an annular niche defined by the shoulder and the collar.

Two or more latches 17 are employed to hold a reinforced sand core suchas 18 in the frame 16.

A flared packing 21 blocks an annular gap between a batten 23 and ajournal 22 of the collar. A series of bolts 24 holds the brim of thepacking 21 tightly between the batten 23 and a girt 25. Axiallyoutwardly from the batten 23 a distance varying with the temperature ofthe mold, a gear 26 is rigidly secured to the collar. Extending radiallyinwardly from the collar, a series of vanes 27 forces water therefromwhen the mold is inundated and rotated.

A sealing hood 29 has axially packed relationship with the plain, orspigot, end of the mold 12. A split collar 30, comprising twosemi-circular halves, is radially supported by the hood 29 andabuttingly engaged by a shoulder 31 of the mold. A series of screws 32,projecting axially from the hood, holds the collar 30 tightly againstthe shoulder 31. Mounted in an annular niche, defined by the hood 29 andan inwardly projecting rim of the collar 30, is a thrust bearing 33which has sliding engagement with a hard race 34 rigidly secured to abuttress or portal 35. A circular series of ports 36 and 37, provided inthe hood 29 and collar 30 respectively, force water therethrough whenrevolved therein.

A flared packing 39, smaller than the flared packing 21, blocks anannular gap between a batten 40 and a journal 41 of the hood. The batten40 cooperates with a series of screws 42 in holding the brim of thepacking 39 tightly against the axially outer face of a girt 43. Acurbing 44, secured to the opposite face of the girt by screws 42, hasaxially adjacent relationship with a flange 45 rigidly mounted on thehood 29. Protruding from the spigot end of the mold 12 is a flared ring46 which has radially supportive engagement with the hood 29 and issecured thereto by a series of screws 47.

As indicated by dashed lines (Figure 4), the box-halves 50, haveradially packed and axially abutting relationship with the girts 25, 43and the portal 35. As shown in Figures 1 and 2, the box-half 50 isprovided with projections 51, to resist the thrust of the box-half 90;and, various other structural featurespockets 52, struts 53, and bosses54to accommodate four rows of rollers 55 in radial engagement with themold 12.

The rows are disposed about equally distant from imaginary planes passedvertically and horizontally through the axis of the mold. Each of therollers is mounted with another roller on the opposite ends of an axle(one in Figure l is shown fragmentarily). The upper rollers 55 aremounted on axles 57 which comprise saddles 58 and arms 59. The lowerrollers 55 are mounted on axles 60 similar to axles 57 but having noarms 59 and, instead of saddles 58, stands 61. All of the axles 57, 60are provided with yokes or thrust arms 63 which project radiallyoutwardly therefrom and have axially abutting relationship with thepockets 52 of the box-half 50. The stands 61 are supported by thestruts, or slides, 53 and restricted laterally outwardly by Wedges 64mounted on brackets 65. Screws 66 serve to adjust the wedges 64; screws67, to hold the brackets 65 tightly on the bosses 54. Arms 59 link theupper axles 57 with pins 68 mounted parallel thereto on the brackets 65.

As brought out in Figure 3, each of the rollers 55 comprises aself-aligning roller bearing 70, a metallic tire 71 mounted on thebearing, a cap 72 disposed in radially packed relationship with thetire, and a series of screws 73 which hold the outer race of the bearingtightly between the cap and a shoulder 74 of the tire.

Each end of the axles 57, 60 is provided with a journal 76 and a smallerjournal 77 extending outwardly therefrom. A stand 61, or saddle 58, ismounted on the journal 76 in axially abutting relationship with a spacer78 mounted on the journal 77'. The inner race of the roller bearing 70is held between the spacer 78- and a nut 79 threaded on the end of theaxle. A sealing ring 80 is pressed against the shoulder 74 of the rollertire by springs 81 supported by the stand- 61, orsaddle 58. An annularpacking 75, mounted on the spacer 78, serves to support the sealing ring80 in a semi-floating manner.

The bearing 70 is thus confined in a chamber 8} defined by the tire 71,the cap 72, the journal 77, the spacer 78 and the ring 80. Grease isintroduced to this chamber 82, via a duct 83 which extends entirelythrough the axle and communicates with piping 84 (Figure Screens 85,mounted in the ends of the duct 83, serve to keep chips from enteringthe bearing 70 and to equalize the pressure of the grease distributed bythe duct,

Rounding out the lowerbox-half equipment buthaving no influence on thecharacter of this invention, are track wheels 86', a draw bar 87, andthe lower section of a guard 88. All air, water and electric supplylines are connected with the upper box-half 90; Brackets 91, 921andbosses 93 are provided thereon to support respectively a motor 95, abearing stand 96, and pressure cylinders 97''. A series of bolts 98serves to hold the box-halves in tightly packed engagement one with theother.

The mold gear 26 is engaged by a gear 100 mounted on a journal 101 anddriven by a pinion 102. A fixture comprising the journal 101 is securedto the bracket 92 by a threaded shaft 103. The pinion 102, is mounted onasp-indie 104 supported by the stand 96 and coupled to, the motor 95.Bolts 195, 106 and 107- serve tosecure respectively the motor 95, thestand 96 and a guard 1118 for the gearing.

The cylinders 97 are directed at the axis of the mold 12, and havepiston rods 110 disposed in abutting relation-. ship with the axlesaddles 58. Screws 111 hold the cylinders in packed engagement with thebosses 93. Piping 112- communicates with the cylinders and a supplymeans for air or water under pressure. Pipe 115 communicates with awater disposal means and a duct 116 extending toward the spigot end ofthe mold. Pipe 117 communicates with a water supply means and a duct(not shown) similar to duct 116 but extending toward the bell end of themold.

It will be noted that the lower box-half 50 is heavily I constructed andbraced to resist the thrust of the cylinders 97 and provide a firm basefor holding the mold 112 axially straight. The axles 57, 60 extend frompoints near the ends of the mold to points near the middle of the mold,an arrangement well constituted to bend the mold as a beam. The pressureon the axles is distributed over wide areas and the critical supportingmembers (53, 6 1, 64, 65) are preferably made from a strong rust proofmaterial such as nickel-chromium steel.

When centrifugally filled with molten iron, the mold is raised intemperature and expanded an amount that varies with any difference inheat-conductivity from spot to spot therein. The axis of the mold movesupwardly and the rods 110 are forced outwardly through the boxhalf 90,as the mold is dilated. If the mold tends to bow,

the pressure on each of the lower rollers fluctuates as the moldrevolves but as long as the minimum pressure on each roller is greaterthan zero, no bowing is realized.

The mold is expanded about 0.04 inch per foot by the heat of the castingand enough to be injured thereby, if held rigidly. The pressure that maysafely be applied by the cylinders 97 is therefore limited and best heldto an amount little more than enough to keep the mold straight. Fourrows of rollers are preferable to three because of the relatively lesssevere pinching action. The pressure required to hold a large moldstraight is still considerable, especially if the mold is sprayed withan sulating compound and re-used as rapidly as possible withoutcleaning.

The necessary roller pressure is not as great, however,

4 as might be gathered from the behaviour of unrestrained molds. A moldfor 12 inch pipe, 18 feet long, is held straight by a roller pressure,of some 4000 pounds, less than enough to remove a bow of 0.05 inch fromthe mold. If a mold is held constantly straight, the interior is abradedvery little more on one side than the other as pipe after pipe iswithdrawn .there-frorn. All sectors are heated about equally andexpanded in a nearly uniform manner.

The power required to drive the sixteen rollers 55 is minimized by thenovel type of grease seal employed, a seal that is not damaged by hot ordirty water and is capable of retaining a grease of low viscosity. Therings are preferably made of resin, reinforced with fabric andinterspersed with graphite, When so made, the friction realized fromthese parts is very low; their useful life, measured in months.

The same non-metallic construction is well-suited for the thrust bearing33-. The material employed for the curbing 44 is of relatively littleimportance if the packing journal 41 is made, as shown, somewhat smallerthan the packing journal 22. The flange 45* is then normally disengagedfrom the curbing 44, by the unbalanced hydraulic force on the rotor 10-.

All molds for the same size of pipe are provided, preferably, withroller paths of the same diameter. The lower rollers are best aligned inthe box-half 50 with the aid of a gage, e.g a specially prepared mold.Little or no allowance is made for wear since the roller paths arereduced but afew mils in diameter during the useful life of the mold (interms of" product cast, about 2000 tons).

Changing fromone mold to another is conveniently accomplished byremoving the box-half and rotating the upper axles 57 about the pins 68until the arms 59 rest on the top face of the box-half 50; The rotor 10can then be lifted from the lower rollers 55 and another rotorsubstituted. Piping 112, 115, 117 comprises swinginghoses and is notdisconnected from the box-half 9.0 in this procedure.

In case a mold of a different diametrical size is to be substituted,certain appurtenances. are replaced; others, reused. The girts 25', 43can be used for-more than one size of mold, as can the gear-and therollers 55. The lower axles 60 are adapted to a second size of mold bysimply inverting the stands 61 which have diametrically opposed basesfor this purpose.

The larger the mold diameter, the greater the expansion and. the morediflicult is it tohold the mold straight by means of a surroundingsleeve. Post extending from the sleeve to the mold must be very looselyengaged or applied via springs. In either case, the bowing action of themold is restricted but not suppressed. Superior castings can be producedby the aforedescribed scheme at no greater cost.

If the girth of the mold barrel is more than 25 percent as great as thelength, the upper rollers can be safely omitted. In any case, the meansrevealed herein for taking the thrust of the mold and for mounting thelower rollers can be employed withbenefit. The extreme ends of the moldare well cooled, under the terms. The thrust bearing is. stronglysupported and copiously lubricated. The rollers are readily adjusted,easily maintained.

I claim:

1. A centrifugal casting; machine which comprises, a long tubular mold,a box surrounding the mold, means for separating upper and lower halvesof the, box, means for rotating the mold, means for resisting theaxialmovement of the mold, and means for holding the mold axiallystraight; said holding means. comprising four rows of rollers engagingthe mold, rotativlyat points equally spaced thereabout, each rowcontaining at least four rollers and two axles for mounting the rollersin widespread pairs, stands supporting two rows of the rollers below themold in laterally sliding relationship with the box, wedges controllingthe laterally outmost position of the stands, means for supporting theother two rows of rollers above the mold in pivoting relationship withthe lower box-half, and cylinders mounted on the upper boxhalf forpressing the upper roller axles toward the axis of the mold.

2. The machine described in claim 1 further characterized by having athrust arm mounted centrally on each axle, and pockets disposed in thelower box-half for resisting the axial movement of the arms.

3. A centrifugal casting machine which comprises a long tubular moldwith an enlarged end, a box surrounding the mold, means for separatingupper and lower halves of the box, a gearing element mounted on theenlarged end of the mold, a guiding element mounted on the opposite endof the mold, rollers cradling the mold for rotation, and means forcirculating water under pressure about the mold; said, guiding elementcomprising an annular hood disposed in packed relationship with theend-face of the mold, an axially split collar which cooperates with ashoulder of the mold and a series of screws in securing the hood, saidcollar having a rim which projects axially inwardly and engages the hoodradially, a thrust bearing mounted in an annular niche defined by theinner end of the hood and the collar, a buttress mounted in the box forengaging the axially inner face of the bearing, a girt having radiallypacked relationship with the box and with a journal provided on thehood, and a flange mounted on the hood in spaced relationship with theaxially inner face of the girt.

4. The machine described in claim 3 further characterized by saidgearing element having a packing journal which is diametrically largerthan the journal of the hood.

5. In a casting machine which comprises a long tubular mold, a housing,and rollers cradling the mold for rotation: stands supporting the rolleraxles and extending thereabove, struts mounted in the housing forsliding the stands thereon, brackets aflixed to the housing in laterallyspaced relationship with the stands, upwardly flared wedges mounted onthe brackets for controlling the laterally outmost position of thestands, screws depending from the bracket for adjusting the verticalposition of the wedges, and means for resisting the longitudinalmovement of the axles.

6. The construction described in claim 5 further characterized by saidstands each having an inverted base and substantially the sameconfiguration.

7. The construction described in claim 5 further characterized by havingrings mounted on the axles between the stands and rollers, annularpackings supporting the rings, springs mounted on the stands forpressing the rings against the rollers, and means for forcing greaseinto the roller while the mold is rotating.

References Cited in the file of this patent UNITED STATES PATENTS1,988,470 Arnold Ian. 22, 1935 2,278,555 Myers Apr. 7, 1942 2,561,360Goss July 24, 1951 2,586,349 Kurtz Feb. 19, 1952 2,790,997 Kurtz May 7,1957 FOREIGN PATENTS 286,479 Great Britain Mar. 8, 1928 182,488 Austn'aJuly 11, 1955 531,346 Canada Oct. 9, 1956

